Fast and Sensitive Determination of Iodide Based on Ternary Chalcogenides Nanoparticles.

A fluorescent probe based on ternary AgFeS quantum dots has been prepared for the design of ternary chalcogenides. The nanoparticles are synthesized with oleylamine as a stabilizer at a low temperature (particle size in the range of 2 to 3 nm) and they exhibit an intense blue emission in aqueous media. As for their internal structure, each nanoparticle's relative stoichiometric ratio (AgFeS) is very close to the theoretical value of 1:1:2. Their magnetic properties have been studied with a vibrating sample magnetometer and they have ferromagnetism between 4 K and 298 K (applied magnetic field ranging between -10,000 and 10,000 Oe). In the presence of iodide ions, the emission at 458 nm derived from AgFeS QDs has been observed to give rise to fluorescence quenching. The detection system is based on a static quenching process and morphological change between iodide ions and AgFeS, which has a good linear range from 0 to 37.5 μmol/L, with a limit of detection of 0.99 μM. The nanoprobe responds within 30 s for the efficient detection of iodide. Such functional quantum dots will provide a powerful indicator in environmental and bio-sensing applications.